Definition of "metropole"

Though the metropole remained confident in its Westminster ways, its newly independent colonies imposed constitutional constraints on the powers of parliament.

2007, Bruce Ackerman, “Meritocracy v. Democracy”, in London Review of Books, 29:5, p. 9

As Europe's population growth and commercial activity slowed down after 1620, its thirst for Spanish-American silver slackened: metropole and colony were drifting apart.

2007, John Darwin, After Tamerlane, Penguin, published 2008, page 63